staging: wilc1000: rename pUserVoid in add_network_to_shadow function

This patch renames pUserVoid to user_void that is
second argument of add_network_to_shadow function to avoid camelcase.

Signed-off-by: Leo Kim <leo.kim@atmel.com>
Signed-off-by: Glen Lee <glen.lee@atmel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>